Konstantinos G. "Costas" Simitis (Greek: Κωνσταντίνος Γ. Σημίτης; born 23 June 1936), sometimes called Costas Simitis or Kostas Simitis (Κώστας Σημίτης), is a Greek politician. He served as Prime Minister of Greece and was leader of the Panhellenic Socialist Movement (PASOK) from 1996 to 2004.[1]